Removing Cryptosporidium-size microspheres with polyaluminium FeCl3

Tao Yuana,b,c, Ping Lub,*

ABSTRACT: Cryptosporidium is a genus of protozoa that infects swimming pools causing diarrhoea and other illnesses. In this study, the removal of Cryptosporidium-size microspheres from a 10 000 l swimming pool was evaluated under varying conditions to provide a reliable and efficient water treatment technique. The baseline condition without coagulation (widely practised in swimming pools today) showed that treating a pool with microspheres at a density of 4000 microspheres per litre through a 33 cm diameter sand filter at 30 m/h flow rate removes 25% of Cryptosporidium-size microspheres. The filtration followed by polyaluminium FeCl3 (PAFC) coagulation results in 99% microsphere removal over the 168 h experimental period with filter backwashing every 48 h. Additionally, the impact of the flow rate and filter cross-sectional area was also examined.